Field of the Invention
The present invention relates to a technique for control power using a sensor.
Description of the Related Art
Currently, some electronic apparatuses such as image processing apparatuses perform control while detecting presence of a user nearby using information from human detection sensors included therein.
In typical control, when an image processing apparatus has not only a normal operation mode but also a power saving mode, in which power consumption is reduced, the image processing apparatus recovers from the power saving mode to the normal operation mode if a user enters a detection range of the human detection sensor during the power saving mode (refer to Japanese Patent Laid-Open No. 11-202690).
In an image processing apparatus disclosed in Japanese Patent Laid-Open No. 11-202690, however, there is a problem in that the image processing apparatus might recover from the power saving state by erroneously detecting a person who does not use the image processing apparatus, such as a passerby, and accordingly power is unnecessarily consumed. This problem may be solved using a method for avoiding erroneous detection by decreasing detection sensitivity and narrowing the detection range of the human detection sensor.
In this case, however, a distance over which an actual operator approaching the image processing apparatus may be certainly detected becomes small and, because the image processing apparatus might still be recovering even when the operator has reached the image processing apparatus, the operator needs to wait for completion of the recovery, which decreases user-friendliness.
As a method for solving this problem, a method may be used in which an approaching operator is detected more accurately by detecting presence of a human in a plurality of regions using a plurality of sensors and analyzing the positions and the order of regions in which the approaching operator has been detected. Since movement of a human within the detection range may be recognized in this method, the movement of the human may be predicted, and the image processing apparatus may begin to recover from the power saving state by predicting that the human is approaching the image processing apparatus.
In this method, however, in order to recognize the state of movement of a human on the basis of detection information from the plurality of regions and predict the future movement direction of the human and the like on the basis of results of the recognition, a simple analysis circuit such as a microcomputer is necessary.
When the image processing apparatus is in the normal operation state, the power consumption of the analysis circuit in a pyroelectric array sensor is considerably smaller than that of a central processing unit (CPU) that controls the entirety of the image processing apparatus or the like.
When the image processing apparatus is in the power saving state, however, the power consumption of the entirety of the image processing apparatus is required to be extremely small, namely, for example, less than 1 W, and therefore the power consumption of the analysis circuit significantly affects the required power consumption.
Thus, it is very difficult to realize both further reduction of power consumption in the power saving state and rapid recovery from the power saving state at a high level.